1. Field of the Invention
The invention relates to an improved tremolo device for use with a stringed instrument such as a guitar. The invention also relates to a stringed instrument having an improved tremolo device.
It is often desired to provide stringed instruments with a tremolo device that allows the instrument to produce its normal tones, but also to produce a tremulous tone effect, by suitable operation of the tremolo device. Existing stringed instruments can also be modified with the tremolo device of the invention. The tremulous tone effects result from changing the tension on the strings of the instrument. While these effects can be produced with other stringed musical instruments such as violins, base guitars, cellos and banjos, the description will be directed to guitars, which include acoustical and electric guitars.
In a conventional guitar, comprised of a body portion, a neck portion and a head portion, the strings attached at the head portion of the instrument, pass over the neck portion of the instrument and then pass over a bridge located in the body portion, and are then attached to the body of the guitar with a tailpiece. When certain tremolo devices known in the prior art are employed, sufficient friction can develop in the mechanisms of their tremolo devices that the tremolo devices may not always return to their original position, thereby resulting in poor sound quality emanating from the guitar.
2. Prior Art
The closest reference to the present invention is disclosed in U.S. Pat. No. 5,392,680 to Stets. Stets is also the inventor of this invention and as clearly alluded to in the title the present invention is a modification of the invention disclosed in U.S. Pat. No. 5,392,680. A difference between Stets' prior invention and this invention is that this invention maintains stability during any string tension change, which includes string breakage. However to appreciate the present invention, we will describe Stets' prior invention and prior modifications in greater detail.
U.S. Pat. No. 5,392,680
FIG. 1 shows a conventional musical instrument such as a guitar 10, which comprises a body portion 11, a head portion 12, a neck portion 13, a multiplicity of strings 14 and a bridge member 15. A tremolo device 16 of the invention is shown attached to the body portion 11 of the guitar 10. Lever 17 of the invention is shown as part of tremolo device 16.
A fragmentary portion of the body portion 11 of guitar 10 is shown in FIG. 2. The tremolo device 16 of the invention is shown attached to body portion 11 by means of metal bolts 29 and 29′ that pass through metal lugs 30 and 30′ and into body portion 11. Pinion gear 20 is joined to bracket 21a of movable plate 21 by means of metal spindles 31 and 31′ that are attached to movable plate 21 and seated in bearings 32 and 32′. In addition to bracket 21a, movable plate 21 has a horizontal portion or component 21b and a vertical portion or component 21c. Lever 17 is shown attached to pinion gear 20. Metal thumb nuts 23 and 23′ together with metal screws 23a and 23a′, respectively, serve to attach metal lock cover 35 to fixed plate 22. Metal spring 24 is attached to movable plate 21 and fixed plate 22 by means of hooks 26 and 28, respectively, that are attached to perches 25 and 27, respectively. The metal spring 24′ is attached to movable metal plate 21 and fixed metal plate 22 by means of hooks 26′ and 28′ respectively, that are attached to perches 25′ and 27′, respectively. The metal springs 24 and 24′ serve to apply tension to counter the tension being exerted by strings 14, to hold movable plate 21 and fixed plate 22 in relative position with respect to each other.
FIG. 2 further shows six strings 14 positioned in essentially parallel direction. The strings extend from the head portion 12 of the guitar 20 as shown in FIG. 1. The strings pass over the saddle notches 55 of the saddle members 54 of bridge member 15. The strings 14 pass through string mounting holes 33 in the vertical portion 21c of movable block 21 and terminate in a suitable terminal end such as terminal rings 34.
FIG. 3 is a side elevation of FIG. 2 which shows a cutaway view of the body portion 11 of guitar 10. Fixed plate 22 is attached to body portion 11 by means of bolt 29′ which passes through metal lug 30′ into body portion 11. Relative positions of fixed plate 22 and movable plate 21 are maintained by the tension applied by strings 14 and the counter tension applied by metal spring 24′. Metal spring 24′ is attached to movable plate 21 and fixed plate 22 by means of hooks 26′ and 28′, respectively, that are attached to perches 25′ and 27′, respectively. String 14 passes over saddle notches 55 of saddle members 54 of bridge 15 and toward movable plate 21. Lever 17 is attached to pinion gear 20. Metal lock cover 35 is attached to fixed plate 22 by metal thumb nut 23 and metal screw 23a as shown in FIG. 5.
FIG. 4 is an end elevation of FIG. 3 generally along line 4-4 in FIG. 2. Fixed plate 22 is attached to body portion 11 by means of metal bolts 29 and 29′ which pass through metal lugs 30 and 30′, respectively, and into body portion 11. Pinion gear 20 is joined to bracket 21a of movable plate 21 by means of metal spindles 31 and 311 that are seated in bearings 32 and 32′, respectively. Metal spring 24 is attached to movable plate 21 and fixed plate 22 by means of hooks 26 and 28, respectively, that are attached to metal perches 25 and 27, respectively, as shown in FIG. 2. Metal spring 24′ is attached to movable plate 21 and fixed plate 22 by means of hooks 26′ and 28′, respectively, that are attached to perches 25′ and 27′, respectively, as shown in FIG. 2. Metal thumb nuts 23 and 23′ pass through horizontal portion 37 and vertical portion 36 of metal lock cover 35 and attach the metal lock cover 35 to fixed plate 22 as shown in FIG. 5. Fixed plate 22 can comprise horizontal component 22a and vertical component 22b which can be made in one piece or can be individually produced and fastened together. Gear racks 40 and 40′ protrude from fixed plate 22 as shown in FIG. 5. Lever 17 is attached to pinion gear 20.
In FIG. 5, fixed plate 22 is attached to the body portion 11 of the guitar 10. A gear rack 40 is attached to the upper surface of the horizontal component 22a of fixed plate 22. A pinion gear 20 is linked to movable plate 21 by means of metal spindles 31 and 31′ at the ends of pinion gear 20, which are fastened in bearings 32 and 32′, which are mounted in brackets 21a on the movable plate 21 as shown in FIG. 2. A lever 17 is attached to the pinion gear 20. Strings 14 pass over the saddle notches 55 of bridge 15, then through string mounting holes 33 in movable plate 21, terminating in a terminal end such as a ring 34. All the components of movable plate 21, that is bracket 21a, horizontal component 21b and vertical component 21c can be cast in one piece or can be individually produced and fastened together.
FIG. 5 further shows the details of the gear rack 40 which is provided with teeth 41. Pinion gear 20 is provided with teeth 43 around the circumference thereof. Lever 17 is preferably provided with a bend 45, and optionally with flat surfaces 46 which can be machined into the surfaces of the lever 17 near where it adjoins with the pinion gear 20. When desired, the lever 17 can be twisted or rotated so that the machined surfaces 46 of the lever 17 can be tightened up in the confines of the slot 48 in the upper portion of the horizontal portion 37 of the metal cover 35, as shown in FIG. 8.
Each string 14 is provided with a bridge member 15. In FIG. 5, the bridge 15 is provided with saddle notch 55 of saddle 54. String 14 rests in the saddle notch 55. The saddle adjustment screws 51 adjust the saddle 54 longitudinally to lengthen or shorten the pitch length of the string 14. Saddle tension spring 52 prevents the saddle 54 from floating or moving on its own. The saddle tension spring 52 provides sufficient tension to retain the adjusted position. The bridge height adjustment screw 53 adjusts the height of the bridge 15. The bridge reference point 56 is situated in the bridge reference groove 57 and is used when needed to find another point of adjustment beyond that normally provided.
Furthermore in FIG. 5, anti-friction bearings such as needle bearings 63 are contained in the cavity created by slots 60 and 61 that have been cut in the opposing faces of fixed plate 22 and movable plate 21, respectively. Bearing cage 62 maintains the bearings 63 in relative position.
In the operation of the tremolo device of the invention, tension in string 14 is decreased by depressing lever 17 which causes pinion gear 20 to rotate, thereby driving the movable plate 21 to cause the tremolo effect when the musical instrument 10 is played. Tension on string 14 is increased by releasing lever 17, and the sound of the instrument returns to is original tone.
FIG. 6 is a vertical section taken along line 6-6 of FIG. 5. Fixed plate 22 is shown attached to body portion 11 by means of metal bolts 29 and 29′ which pass through lugs 30 and 31′, respectively, into body portion 11. The tension applied by strings 14 and the opposing or counter tension applied by metal springs 24 and 241 serve to maintain the relative position of fixed plate 22 and movable plate 21. Perches 27 and 27′ protrude from movable plate 21. Hooks 28 and 28′ engage the perches 27 and 27′, respectively, as shown in greater detail in FIGS. 2 and 3. Metal thumb nuts 23 and 23′ attach metal lock cover 35 as shown in FIG. 3 and FIG. 5. String mounting holes 33 permit the passage of strings 14 into and through the movable plate 21. Slots 60 and 60′ are machined in the upper face of fixed plate 22. Slots 61 and 61′ are machined in the lower face of movable plate 21. These slots form cavities 64 and 64′ for insertion of anti friction bearings, such as needle bearings 63 and 63′. Bearing cages 62 and 62′ made of plastic material maintain the bearings 63 and 63′ in their proper relative positions within cavities 64 and 64′.
FIG. 7 is a reduced vertical section taken along line 7-7 in FIG. 5. Fixed plate 22 is attached to body portion 11 by metal bolts 29 and 29′ which pass through metal lugs 30 and 30′, respectively into body portion 11, as shown in FIG. 6. The horizontal component 22a and the vertical component 22b are show in FIG. 7. Fixed gear racks 40 and 40′ are attached to the horizontal component 22a of fixed plate 22. Pinion gear 20 is attached to movable plate 21 at brackets 21a and 21a′ by means of metal spindles 31 and 31′ seated in bearings 32 and 32′, respectively. Metal thumb nuts 23 and 231 are used to attach metal lock cover 35 to the fixed plate 22 with the aid of metal screws 23a as shown in FIG. 5. Metal springs 24 and 24′ are used to hold movable plate 21 in relative position to fixed plate 22 by virtue of the tension applied by strings 14 which balances the counter tension applied by the metal springs 24 and 24′. Lever 17 is attached to pinion gear 20.
FIG. 8 is a greatly enlarged fragmentary section taken along line 8-8 of FIG. 5. Horizontal portion 37 of metal lock cover 3S has a slot 68 into which is inserted lever 17 at its machined surface 48. The structure allows for lever 17 to lock when rotated in fixed a position when the tremolo effect is not desired. When a tremolo effect is desired lever 17 is rotated out from the locked position.
The tremolo device of the invention is suitable for use in various stringed instruments, such as acoustic and electric guitars, base guitars, violins, cellos an banjos. The strings for such instruments are generally six in number, but there can be as many as 12 strings. Base guitars generally have 4, 5, or 6 strings. The strings for such instruments can be made of nickel alloys, stainless steels, brass and plastics such as nylon. The body of stringed instruments is generally made of wood. Some stringed instruments have some metal parts.
The tremolo device of the invention can be made of various metals. The fixed and movable plates are generally made of low carbon steel or bronze. The gear rack and pinion gear are generally made of brass or low carbon steel.
The bearings are preferably needle bearings, but other bearings, such as roller or ball bearings can be employed.
The bearing cage materials can be made of plastics, such as nylon or polyoxymethylenes (Delrin).
Modifications to Stets Design
Around the year 2000, Stets modified the rack and pinion system identified in U.S. Pat. No. 5,392,680. The rack and pinion system of the prior art was replaced with a conventional swing link mechanism 800 to render the product easier to manufacture. FIGS. 9 and 10 illustrate the swing link mechanism 800 modification.
In the swing link mechanism modification, the fixed plate 22 was divided into two components—(1) a mounting fix plate 722 which is designed to be positioned against the original component of the string instrument, and (2) a retainer 724 having a U shape configuration having an exterior surface 725 and an interior surface 726. On the exterior surface 725, U shape configured retainer 724 has a bottom side 727 that connects to the mounting fix plate 722, a riser side 728 that faces the movable plate 21, a top side 730, a right edge 732 and a left edge 734.
In the interior surface 726 is a track adjuster 740. The track adjuster 740 has the perches 27 and 27′ that extend beyond the retainer's right and left edges 732, 734. The biasing members' 24, 24′ hooks 28, 28′ respectively connect to the perches 27, 27′. The track adjuster 740 also has two apertures that receive tension adjusting screws 23, 23′. The tension adjusting screws 23, 23′ are designed to contact (see phantom lines) the interior surface 726 of the riser side 728 to adjust the distance of the track adjuster from the moving plate 21, which in turn adjusts the tension of the biasing members 24, 24′. Once the tension adjusting screws 23, 23′ are set, the track adjuster 740, the mounting fix plate 722 and the retainer 724 do not move (except when the tension adjusting screws are adjusted), even when the lever 17 is moved.
The moving plate 21 also has a first bracket 700 and a second bracket 700′ that extend from the moving plate's vertical portion 21c toward the retainer 724 (or away from the bridge 15). In particular the first and second brackets 700, 700′ (a) have a first aperture 702, 702′, (b) have a second aperture or a second perch 704, 704′ that secure the biasing members' 24, 24′ hooks 26, 26′ to the moveable plate 21, and (c) align with the retainer's right and left edges 732, 734.
The lever 17 interconnects to a conventional swing link 800, in particular a top side 801 of the swing link 800. The swing link 800 has the top side 801, a length (l) that fits between the two brackets 700, 700′, a first aperture 803, 803′ at each bracket end that corresponds to a respective bracket's first aperture 702, 702′, a rounded bottom side 802, 802′, a second aperture 808, 808′ that is positioned within the radius of the rounded bottom sides 802, 802′, and a gap area (not shown) between the two rounded sides 802, 802′. The rounded bottom side 802 contacts the mounting fix plate 722 while the gap area fits over a locator plate 850. The locator plate 850 is affixed to the mounting fix plate 722 and is positioned in between the exterior riser side 728 and the moving plate 21. The locator plate 850 has an aperture 852, 852′ that corresponds with the second aperture 808, 808′ to allow a pin (not shown) connect the locator plate 850 to the swing link 800 so that when the lever 17 is moved up or down in relation to the musical instrument the movable plate 21 moves forward or backward the desired distance.
In this embodiment, (1) when the lever 17 is moved down (toward the musical instrument), the biasing members 24, 24′ increase in tension and the moving plate 21 moves away from the retainer 724; (2) when the lever 17 is in the relaxed state (not being moved) the biasing members 24, 24′ continue to provide tension but not as much as when the lever 17 is moving down and the moving plate remains in place; and (3) when the lever 17 is moved up, (a) the biasing members 24, 24′ decrease in tension, (b) the retainer 724 and the track adjuster 740 do not move, and (c) the moving plate 21 moves toward the retainer 724. These facts are important in distinguishing the prior art from the claimed invention because the present invention maintains stability during any string tension change, which includes string breakage, and the prior art does not because of that movement.